Abstract: Subproject 2 WS. Vulvar Vestibulitis Syndrome (WS), the most common type of chronic vulvo-vaginal pain, negatively impacts the psychological, physical, and reproductive health of approximately 10% of women at some point in their life. Despite decades of research, the etiology and pathophysiology of WS remain unknown. Current treatments are largely empiric and guided more by an individual clinician's prior experience and comfort level than objective data on therapeutic efficacy. Recent evidence suggests that the etiology of WS involves impairment of biological and psychological processes, similar to those of other chronic pain disorders. Although women diagnosed with W S present with a spectrum of mucosal sensitivity, pelvic muscle dysfunction, and psychological distress, the actual diagnosis of WS continues to rely on relatively crude measures of mucosal sensitivity (cotton swab palpation and patient report of pain) on clinical exam. A lack of strict criteria for evaluation, and dependence on highly subjective measures by both clinician and patient, suggests that this diagnosis is currently poorly circumscribed. As such, it is likely to encompass a heterogeneous, potentially divergent group of women with the sole common feature of frustration with persistent vulvar pain and dyspareunia.